Zinc (II)-based metal organic framework crystalline material and preparation method and application thereof

Abstract

The invention relates to the technical field of fluorescent active substances, in particular to a zinc (II)-based metal organic framework crystalline material as well as a preparation method and application thereof. The molecular formula of the zinc (II)-based metal organic framework crystalline material is [Zn (NH2-BDC) 2 (BMIP) 2] n, zinc (II) ions serve as connecting nodes, BMIP and NH2-BDC ligands serve as bridging ligands to be in bridge connection, a three-dimensional space structure is formed, an asymmetric structural unit of a crystal comprises a BMIP ligand and a deprotonated 2-amino terephthalic acid ligand, and the molecular formula of the zinc (II)-based metal organic framework crystalline material is as shown in the specification. And the zinc ion is of a four-coordinated asymmetric tetrahedral configuration. The divalent zinc ion fluorescence sensing material can be prepared by adopting a one-pot solvothermal reaction, and the zinc (II) fluorescence sensing material is relatively high in fluorescence emission spectrum intensity and can be applied to the fields of molecular fluorescence probes, metal ion detection and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of fluorescent active substances, and in particular to a zinc (II)-based metal organic framework crystalline material and a preparation method and application thereof. Background Art

[0002] With the acceleration of industrialization, various harmful ions, such as heavy metal ions and cyanide ions, enter the environment, posing a threat to ecosystems and human health. For example, thorium is discharged with wastewater and wastewater during rare earth ore mining and processing, causing radioactive environmental contamination. Furthermore, certain ions require rapid and accurate detection in industrial production, medicine, and other fields to ensure process safety and product quality. Traditional detection methods, such as gas chromatography, liquid chromatography, and elemental analyzers, while highly accurate, suffer from complex sample pretreatment, expensive equipment, and cumbersome operation, making them inadequate for rapid on-site detection and real-time monitoring. Therefore, the development of a rapid, convenient, highly sensitive, and low-cost ion detection method is of great practical significance. Furthermore, soil pollution is a serious threat. Pollutants such as heavy metals, pesticide residues, and microplastics accumulate in the soil, posing a threat to crop growth and human health.

[0003] Fluorescence detection technology, with its advantages of high sensitivity, good selectivity, fast response, and ease of operation, has garnered widespread attention in the field of ion detection. Fluorescence sensing ion detection technology based on metal-organic frameworks (MOFs) combines the advantages of MOFs with fluorescence detection technology. Through the interaction between MOFs and target ions, changes in the fluorescence signal are induced, enabling qualitative and quantitative analysis of ions. For example, MOFs can be imbued with fluorescent properties by introducing fluorescent metal ions (such as rare earth metal ions) or organic ligands.

[0004] When target ions interact with MOFs, their fluorescence emission is affected, such as fluorescence quenching, enhancement, or wavelength shift. By detecting changes in these fluorescence signals, the ions can be detected. In recent years, MOFs have achieved fruitful results in the field of fluorescence sensing ion detection. Researchers have developed a variety of MOFs-based fluorescent sensors for detecting various anions, cations, and organic compounds in water. For example, they are used to detect fluoride ions, phosphates, copper ions, iron ions, etc. At the same time, with the continuous deepening of research, two-dimensional MOFs nanosheets have shown greater advantages in detection sensitivity, response speed, and detection limit due to their ultra-thin morphology, larger specific surface area, and more exposed active sites, becoming one of the research hotspots in this field.

[0005] In the future, the development trend of MOFs in the field of fluorescence sensing ion detection will be towards higher sensitivity, better selectivity, more convenient operation and wider application fields. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and provide a zinc (II)-based metal organic framework crystalline material and its preparation method and application, and to prepare the zinc (II)-based metal organic framework crystalline material [Zn(NH2-BDC)2(BMIP)2] by a one-pot solvent thermal reaction. n The preparation method has the advantages of simple process, convenient operation, high yield and good reproducibility. n Can be used as a test for Y 3+ fluorescent probes.

[0007] The present invention provides a zinc (II) based metal organic framework crystalline material, wherein the single crystal molecular formula of the zinc (II) based metal organic framework crystalline material is C 19 H 21 N5O4Zn, the chemical formula of the zinc (II) based metal organic framework crystalline material is [Zn(NH2-BDC)2(BMIP)2] n .

[0008] According to the zinc (II)-based metal organic framework crystalline material provided by the present invention, the zinc (II)-based metal organic framework crystalline material is a tetragonal crystal system with a space group of P43, and the unit cell parameters include a=8.7229(4) Å, b=8.7229(4) Å, c=26.346(2) Å, α=90.00°, β=90.00° and γ=90.00°.

[0009] The present invention provides a method for preparing the above-mentioned zinc (II)-based metal organic framework crystalline material, comprising the following steps: S1. Add zinc salt, BMIP and NH2-BDC to DMF to obtain a mixed solution, and fully react at a constant temperature in a sealed environment to obtain a reaction product; S2. Cooling the reaction product obtained in S1 to crystallize, and washing, filtering and drying the crystallized product in sequence to obtain a Mn(II) coordination polymer photoelectrode crystalline material.

[0010] According to the preparation method provided by the present invention, the BMIP in S1 is 1,3-bis(dimethylimidazolylpropane), and its structural formula is: .

[0011] According to the preparation method provided by the present invention, the NH2-BDC in S1 is 2-aminoterephthalic acid, and its structural formula is: .

[0012] According to the preparation method provided by the present invention, the zinc salt in S1 is zinc nitrate hexahydrate, and the ratio of the zinc salt, BMIP, NH2-BDC and DMF is 0.15 mmol: 0.05 mmol: 0.009 g: 4 mL.

[0013] According to the preparation method provided by the present invention, the temperature for the constant temperature full reaction in S1 is 90° C., and the time for the constant temperature full reaction is 48 h.

[0014] According to the preparation method provided by the present invention, the rinsing agent in S2 is deionized water, the filtration is reduced-pressure filtration, the drying temperature is 60° C., and the drying time is 3 h.

[0015] The present invention also provides an application of a zinc (II) based metal organic framework crystalline material, wherein the zinc (II) based metal organic framework crystalline material is used to detect Y 3+ fluorescent probes.

[0016] The zinc (II)-based metal organic framework crystalline material is [Zn(NH2-BDC)2(BMIP)2] n， It uses zinc (II) ions as connecting nodes, BMIP and NH2-BDC ligands as bridging ligands to bridge each other to form a three-dimensional spatial structure. The asymmetric structural unit of the crystal contains a BMIP ligand and a deprotonated 2-aminoterephthalic acid ligand. The zinc ion is a four-coordinate asymmetric tetrahedral configuration. Two of the nitrogen atoms come from the imidazole nitrogen atoms (N2, N4) in two different BMIP ligands, and the other two oxygen atoms come from two different monodentate oxygen atoms (O1, O3) in 2-aminoterephthalic acid. Compared with the prior art, the present invention has the following advantages: The present invention provides a zinc (II)-based metal organic framework crystalline material and a preparation method and application thereof. The zinc (II)-based metal organic framework crystalline material can be prepared by a one-pot solvent thermal reaction. The preparation method has the advantages of simple process, convenient operation, high yield, good reproducibility, etc. The fluorescence emission spectrum intensity of the zinc (II)-based metal organic framework crystalline material is strong and can be applied to the fields of molecular fluorescence enhancement or quenching effect, metal ion detection, etc. The detection method of the zinc (II)-based metal organic framework crystalline material has the advantages of simple operation, low cost, high selectivity, fast detection speed, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a single molecule image of a zinc (II)-based metal organic framework crystalline material; Figure 2 It is a three-dimensional porous framework structure of zinc (II)-based metal organic framework crystalline material; Figure 3 This is the IR spectrum of zinc (II) based metal organic framework crystalline material; Figure 4 This is the XRD pattern of zinc (II) based metal organic framework crystalline material; Figure 5 This is the fluorescence spectrum of zinc (II) based metal organic framework crystalline material; Figure 6 The fluorescence emission intensity diagram of zinc (II) based metal organic framework crystalline materials dispersed in 7 organic solvents; Figure 7 Y 3+ Schematic diagram of the specificity of ion detection; Figure 8 This is a graph showing the relationship between the fluorescence spectrum of zinc (II)-based metal organic framework crystalline materials in water solvent and the change of metal ion concentration; Figure 9 It is a zinc (Ⅱ) based metal organic framework crystalline material with Y 3+ Schematic diagram of fluorescence intensity changes and fitting with solution concentration. DETAILED DESCRIPTION

[0018] Example 1

[0019] This embodiment provides a method for preparing a zinc (II)-based metal organic framework crystalline material, comprising the following steps: S1. 0.15 mmol of zinc nitrate hexahydrate, 0.05 mmol of BMIP (1,3-bis(dimethylimidazolylpropane), n is a positive integer), 0.009 g of 2-aminoterephthalic acid (NH2-BDC), and 4 mL of N,N'-dimethylformamide (DMF) were mixed to obtain a mixture. The mixture was solvothermally reacted in a glass scintillation vial at 90°C for 48 h to obtain a reaction product. S2. The reaction product was naturally cooled and crystallized, the crystals were rinsed with deionized water, and filtered under reduced pressure to obtain colorless cluster crystals, which were placed in an oven at a constant temperature of 60°C for 3 h to obtain a zinc (II)-based metal organic framework crystalline material.

[0020] Comparative Example 1 This comparative example provides a preparation method under conditions different from those of Example 1, comprising the following steps: S1. 0.15 mmol of zinc nitrate hexahydrate, 0.05 mmol of BMIP, 0.009 g of 2-aminoterephthalic acid, 4 mL of N,N'-dimethylformamide, and 50 μL of glacial acetic acid were mixed to obtain a mixture. The mixture was subjected to a solvothermal reaction at 90°C in a glass scintillation vial for 48 h to obtain a reaction product. S2. The reactants were cooled naturally to obtain a clear and transparent solution.

[0021] The reason why no crystallization occurred in Comparative Example 1 was that the pH of the reaction system did not match. Under acidic conditions (the amount of glacial acetic acid added was greater than 50 μL), it was difficult for this system to precipitate crystals.

[0022] Example 2 This example characterizes the zinc (II)-based metal organic framework crystalline material prepared in Example 1, including the following aspects: ① Crystal structure determination of zinc (Ⅱ)-based metal organic framework crystalline materials Select the appropriate size of 0.15×0.12×0.1 mm under the microscope 3 X-ray diffraction experiments were performed on single crystals at room temperature. Diffraction data were collected on a Bruker P4 CCD single crystal diffractometer and monochromated with a graphite monochromator. Mo-Kα ray (λ = 0.71073 Å), with φ-ω Diffraction points were collected using a scanning method. Furthermore, absorption and factor corrections for Lp were performed using the SADABS program. Full-matrix least-squares corrections were performed for all non-hydrogen atoms and their anisotropic thermal parameters using the SHELX-97 program. Detailed crystallographic data are shown in Table 1, and important bond length and bond angle data are shown in Table 2.

[0023] Table 1 Main crystallographic data of Zn(II)-based metal-organic framework crystalline materials

[0024] Table 2 Important bond lengths (Å) and bond angles (°) of Zn(II)-based metal-organic framework crystalline materials

[0025] Symmetric code: 1 -Y,1+X,-1 / 4+Z; 2 -1+Y,-X,1 / 4+Z; 3 1-Y,-1+X,-1 / 4+Z; In Table 1, a, b, and c represent the edge lengths of the crystal in the directions of the three crystal axes, and α, β, and γ represent the angles between a and b, a and c, and b and c, respectively; Zis the number of molecules contained in the unit cell; the diffraction index range of the limiting factor is (h, k, l); F(000) is the number of electrons in the unit cell; Final 1 R indices [I>2σ(I)] is the residual factor R value for the observable diffraction point; R is the non-weighted consistency factor; R1 and wR2 are both weighted consistency factors; In the first row of Table 2, Zn(1) refers to Zn atom 1 in the Zn(II)-based metal organic framework crystalline material single crystal, N(2) refers to N atom 2 in the Zn(II)-based metal organic framework crystalline material single crystal, Zn(1)-N(2) represents the bond length between Zn atom 1 and N atom 2, and the bond length is 1.953±11, with 11 being the standard deviation; N(2)-Zn(1)-N(4) represents the bond angle between N atom 2, Zn atom 1 and N atom 4, and the bond angle is 106.9±4; Crystal structure such as Figure 1 As shown, the molecular formula of zinc (II) based metal organic framework crystalline material is [Zn(NH2-BDC)2(BMIP)2] n， It uses zinc (II) ions as connecting nodes, BMIP and NH2-BDC ligands as bridging ligands to bridge each other to form a three-dimensional spatial structure. The asymmetric structural unit of the crystal contains a BMIP ligand and a deprotonated 2-aminoterephthalic acid ligand, and the zinc ion is a four-coordinated asymmetric tetrahedral configuration.

[0026] Two of the nitrogen atoms come from imidazole nitrogen atoms (N2, N4) in two different BMIP ligands, and the other two oxygen atoms come from two different monodentate oxygen atoms of 2-aminoterephthalic acid (O1, O3).

[0027] ②IR spectrum characterization of zinc (Ⅱ)-based metal organic framework crystalline materials Figure 3 This is the IR spectrum of the zinc (II)-based metal organic framework crystalline material. The sample infrared spectrum data was collected from 500 to 4000 cm -1 , using KBr pellets.

[0028] Depend on Figure 3 It can be seen that the Zn(Ⅱ)-based metal organic framework crystalline material has a -1 There is a strong broad absorption peak at 1608 cm, which is the stretching vibration peak of the -NH group. -1 The asymmetric and symmetric stretching vibrations of the carbonyl group are shown.

[0029] The molecular formula of the material is [Zn(NH2-BDC)2(BMIP)2] n , n is a positive integer.

[0030] ③ Phase purity characterization of Zn(Ⅱ)-based metal-organic framework crystalline materials The powder XRD characterization results of zinc (II) based metal organic framework crystalline materials using Bruker / D8Advance X-ray diffractometer show that they have reliable phase purity, which provides a guarantee for their use as fluorescent probes to detect excessive organic pollutants, pesticides, and heavy metal ions emitted in the environment. Figure 4 shown.

[0031] ④ Solid-state fluorescence characterization of Zn(Ⅱ)-based metal-organic framework crystalline materials The solid fluorescence properties of Zn(II)-based metal organic framework crystalline materials were tested using Edinburgh instruments / FLS 1000 fluorescence spectrometer. Figure 5 As shown, the zinc (II)-based metal organic framework crystalline material has a strong fluorescence emission peak at 414 nm with an excitation wavelength of 347 nm.

[0032] Example 3 2.0 mg of the fully ground zinc (II)-based metal organic framework crystalline material powder prepared in Example 1 was weighed and placed in 7 4 mL organic solvents respectively. After ultrasonication for half an hour and standing for one hour, the supernatant was taken and placed in a cuvette.

[0033] The fluorescence emission intensity of the suspension was measured at an excitation wavelength of 347 nm in diethanolamine (DEA), N,N'-diethylformamide (DEF), ethanol (EtOH), acetonitrile (ACN), water, N,N'-dimethylacetamide (DMA) and N,N'-dimethylformamide (DMF) as solvents. Figure 6 shown.

[0034] Depend on Figure 6 It can be seen that the fluorescence intensity of zinc (II)-based metal organic framework fluorescent sensing material in water is the strongest.

[0035] Example 4 2 mg of the thoroughly ground crystalline powder of the zinc (II)-based metal organic framework crystalline material prepared in Example 1 was placed in 4 mL of water, sonicated for half an hour and allowed to stand for one hour, and then 3 mL of the supernatant was placed in a cuvette.

[0036] At an excitation wavelength of 347 nm, 19 different metal cations (Y 3+ 、Gd 3+ 、Er 2+ 、Ho 3+ Sc 3+ 、Pr 3+ 、Dy 3+ 、Nd 3+ 、Hg2+ 、Fe 3+ 、Co 2+ Cr 3+ 、Cu 2+ 、Al 3+ 、Cd 2+ , Ca 2+ 、Zn 2+ 、Ba 2+ The aqueous solutions of , Blank) were added into the supernatant of Zn(II)-based metal organic framework crystalline material in sequence, and the corresponding fluorescence response effects were measured, such as Figure 7 shown.

[0037] Depend on Figure 7 It can be seen that the Zn(Ⅱ)-based metal organic framework crystalline material has a great influence on Y 3+ There is a significant fluorescence quenching effect.

[0038] Example 5 In order to further study the preparation of [Zn(NH2-BDC)2(BMIP)2] n Y 3+ The sensitivity and selectivity of ion detection were further studied by quantitative titration experiments. 3+ ion detection capabilities, such as Figure 8 As shown, it can be clearly found that [Zn(NH2-BDC)2(BMIP)2] n The fluorescence intensity of Y 3+ The concentration of ions gradually increased and showed a trend of gradually weakening. 3+ ions, the fluorescence intensity is about one third of the original.

[0039] According to the above experimental data, the supernatant of ethanol of zinc (II) based metal organic framework crystalline material was further analyzed. I / I 0 value( I represents the fluorescence intensity of Zn(II)-based metal organic framework crystalline material in ethanol solvent after adding organic solvent; I 0 represents the fluorescence intensity of zinc (II) based metal organic framework crystalline material in water solvent when no organic solvent is added) and the metal ion Y 3+ The linear regression equation of the ion aqueous solution was further calculated based on 3σ / slope (σ is the standard deviation of the fluorescence emission intensity of 11 groups of blank experiments, and the slope value is obtained from the linear calibration curve of fluorescence intensity and target ion concentration). n Y 3+ The limit of detection (LOD) of yttrium ion is 1.63389×10 -6 mol / L.

[0040] according to Figure 9 It can be seen that [Zn(NH2-BDC)2(BMIP)2] n The fluorescence emission spectrum intensity increases with the 3+ The concentration of Y 3+ The concentration reached 270 μmol·L -1 When , the fluorescence intensity of the coordination polymer no longer decreases and gradually levels off.

[0041] [Zn(NH2-BDC)2(BMIP)2] n The fluorescence intensity of Y 3+ The concentration showed a good linear relationship (R 2 =0.9763), which shows that [Zn(NH2-BDC)2(BMIP)2] n Can sensitively detect Y in aqueous solution 3+ ion.

[0042] According to the prepared coordination polymer [Zn(NH2-BDC)2(BMIP)2] n Yes, there is Y 3+ The fluorescence quenching effect is obvious, so [Zn(NH2-BDC)2(BMIP)2] n Can be used as a new type of detection Y 3+ fluorescent probes.

[0043] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A zinc (II)-based metal organic framework crystalline material, characterized in that: The single crystal molecular formula of the zinc (II) based metal organic framework crystalline material is C 19 H 21 N5O4Zn, the chemical formula of the zinc (II) based metal organic framework crystalline material is [Zn(NH2-BDC)2(BMIP)2] n .

2. The zinc (II)-based metal organic framework crystalline material according to claim 1, characterized in that: The zinc (II)-based metal organic framework crystalline material is a tetragonal crystal system with a space group of P43, and the unit cell parameters include a=8.7229(4) Å, b=8.7229(4) Å, c=26.346(2) Å, α=90.00°, β=90.00° and γ=90.00°.

3. A method for preparing a zinc (II)-based metal organic framework crystalline material according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Add zinc salt, BMIP and NH2-BDC to DMF to obtain a mixed solution, and fully react at a constant temperature in a sealed environment to obtain a reaction product; S2. Cooling the reaction product obtained in S1 to crystallize, and washing, filtering and drying the crystallized product in sequence to obtain a Mn(II) coordination polymer photoelectrode crystalline material.

4. The preparation method according to claim 3, characterized in that The BMIP described in S1 is 1,3-bis(dimethylimidazolylpropane), and its structural formula is: 。 5. The preparation method according to claim 3, characterized in that The NH2-BDC described in S1 is 2-aminoterephthalic acid, and its structural formula is: 。 6. The preparation method according to claim 3, characterized in that The zinc salt in S1 is zinc nitrate hexahydrate, and the ratio of the zinc salt, BMIP, NH2-BDC, and DMF is 0.15 mmol: 0.05 mmol: 0.009 g: 4 mL.

7. The preparation method according to claim 3, characterized in that The temperature for the constant temperature full reaction in S1 is 90° C., and the time for the constant temperature full reaction is 48 h.

8. The preparation method according to claim 3, characterized in that The rinsing agent in S2 is deionized water, the filtration is reduced-pressure filtration, the drying temperature is 60° C., and the drying time is 3 h.

9. A use of a zinc (II)-based metal organic framework crystalline material according to any one of claims 1-2, characterized in that: The zinc (II) based metal organic framework crystalline material is used to detect Y 3+ fluorescent probes.

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